An apparatus of the type described above is known from EP 0 264 144 A2. Several cavities are arranged under the surface of the body immersed in the flow. Each cavity has an opening leading to the flow at the body immersed in the flow. A loudspeaker is positioned at the edge of each cavity, with which compressional vibrations can be created in the cavity. As a consequence of the compressional vibrations in the cavity, the flow medium, i.e. generally air, enters and leaves through the opening in the cavity. In this way, the flow at the immersed body is exited by means of blowing and suction. As a consequence of this excitation, the complete flow separation from the immersed body is delayed. This means that it results only at a larger angle of incidence and/or at lower speeds of the immersed body relative to the flow, i.e. at lower Reynolds' numbers. However, the known apparatus is complex in construction. Equipment includes not only the cavities and the loudspeakers but also an energy supply to the loudspeakers must be provided.
It is the object of the invention to provide an apparatus with extremely simple construction for influencing the separation of a flow from a body immersed in the flow, which can be realized at low costs.